Literaturdatenbank
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Wells, R. W. (2002). Taxonomic notes on some australian freshwater turtles of the genera chelodina and elseya (reptilia: chelidae). Australian Biodiversity Record, 2, 1–30.
Added by: Admin (14 Aug 2008 20:35:33 UTC) Last edited by: Beate Pfau (10 Jan 2009 15:33:09 UTC) |
| Resource type: Journal Article BibTeX citation key: Wells2002c View all bibliographic details  |
Categories: General Keywords: Australien = Australia, Chelidae, Chelodina, Elseya, Elseya dentata, Elseya lavarackorum, Elseya stirlingi, Habitat = habitat, Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Wells Collection: Australian Biodiversity Record |
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Chelodina Elseya Hello all, here is a part of my recent article on the Australian Chelidae that appeard in Aust.Bio.Rec., 2002 (2): 1-30 As it is too long to post in one slab, herein the Elseya dentata complex comments: From: Taxonomic Notes on Some Australian Freshwater Turtles of the Genera Chelodina and Elseya (Reptilia: Chelidae). by Richard W. Wells “Shiralee”, Major West Road, Cowra, New South Wales, Australia (Part 2) Victoria River Turtle Elseya dentata (Gray, 1863) This is a large species of Chelid turtle about which little is known due to the remoteness of its habitat, as well as past taxonomic conservatism. It was once considered to be a single, widespread and highly variable species that occurred across the tropical north of Australia, but in recent years it has emerged that there are several different species comprising the old concept of Elseya dentata. Specimen collections in recent years have revealed that this so-called single widespread ‘species’ actually has a much smaller distribution than previously thought - Elseya dentata (sensu stricto) is actually restricted to the Victoria River system. Diagnosis: The head is very broad and deep, with a very wide mandibular symphysis and a distinct median alveolar ridge on the upper jaw. The horny plate on top of the head does not extend laterally and there are two small white barbels under the chin. The neck is large and muscular with scattered enlarged conical tubercles over a covering of smaller flat tubercles. The mature carapace is robust, thick and smoothly rounded anteriorly, generally oval in shape and with some posterior expansion. Additionally, there is slight upturning at the lateral marginals but the posterior of the carapace is largely unserrated. In general shape, the posterior margin of the carapace is acutely tapered, not at all rounded in shape. The plastron is always long and relatively narrow, being widest at the bridge and gently tapering both anteriorly and posteriorly, although the anterior plastral lobe does tend to slightly widen with age. The intergular shield completely separates the gulars, and is longer than wide, and much narrower than the adjacent gular shields. Hatchlings differ somewhat in that they have a noticeably serrated posterior margin to the carapace and fairly prominent central ridging (both characters which are lost with age), and some lateral upturning to the carapace as well. In immature specimens, the carapace is pale to light brown, but with age it changes to very dark brown in colouration. Mature individuals have the dorsal colour of the head and neck a uniform dark greyish-brown, and no facial striping, however laterally these areas are much paler - and may even have a piebald or blotched pattern, to being almost totally white in some older specimens. The iris is brownish, with a very light inner ring and is distinctly flecked with darker brown, and usually the tympanic region is whitish also. The ventral colouration is distinctly variegated or piebald in pattern in both sexes, unlike other members of the dentata-complex which are either very pale or very dark and usually unpatterned. Elseya dentata attains a maximum carapace length of around 340mm, but this size would be exceptional, as most mature specimens are only about 280-300mm. Further Comments on the Elseya dentata complex that occur elsewhere: As mentioned above, Elseya dentata is generally regarded by other authors as a single widespread species, occurring in most major river systems of the tropical part of Australia but I personally do not hold this view. Turtles loosely identified as Elseya dentata have been recorded across most of the northern inland, as well as from many of the river systems of north-eastern Queensland, across most of the far north of the Northern Territory, and into the Kimberley Zone of Western Australia, to about as far south as the King Edward River system. However, the obvious variation in morphology suggests that Elseya dentata is clearly composite. Accordingly, I feel that Elseya dentata sensu stricto should be restricted to the Victoria River system of the north-western NT and north-eastern part of WA. Elseya dentata usually prefers the deeper sections of water, but may be found congregating in seasonally dry waterholes as the upper reaches of the river cease to flow with the Dry Season advances. Its reproductive biology is not well-known, but they may lay about 10 eggs in a clutch around the end of the Wet Season (February-May), and these hatch after about 4 months incubation. This is a mainly herbivorous turtle, feeding on various fruits that fall into the water from riparian vegetation (such as Pandanus), as well as aquatic weeds. Captive specimens also consume a range of aquatic invertebrates, small fish and carrion. It is a diurnal as well as nocturnal species that lives mainly in the slower flowing or still-water conditions of its habitat - often large numbers may co-exist together in billabongs beside watercourses or in larger waterholes at the base of low rocky rapids or falls. Specimens will bask on exposed rocks and logs, but will rapidly retreat to the safety of deeper water or under overhanging river banks when disturbed. It is a very long-lived species - probably exceeding 20 years - and it matures very slowly, with males becoming sexually mature at about 9 years, but females not reaching reproductive age until around 13 years old. This species is protected under the WA Wildlife Conservation Act 1950 (as amended), and the Territory Parks and Wildlife Conservation Act (1998). Those turtles regarded as 'dentata' to the west of the Victoria River (in the Kimberley Division of WA) and those to the north-east (in the Daly River, NT) are considered by me to be undescribed taxa. In regards to the populations of 'Elseya dentata' in eastern Australia, see Elseya stirlingi Wells and Wellington, 1985 which has been previously applied to the Atherton Tableland population. That population confined to the Fitzroy-Dawson River system of north-eastern Queensland, is another undescribed species of Elseya, and this appears to be quite distinct from the similarly undescribed Mary River and Burnett River, Queensland populations. Of the population of 'Elseya dentata' that is confined to the Alligator Rivers system in the tropical north of the Northern Territory, I herein formally name as: Elseya jukesi sp. nov. Type Locality: Pul Pul Creek, South Alligator River, Northern Territory. Diagnosis: Elseya jukesi is similar in most morphological characters to Elseya dentata, with which it has previously been associated, as the head is very broad and deep, with a very wide mandibular symphysis and a distinct median alveolar ridge on the upper jaw. The horny plate on top of the head does not extend laterally and there are two small white barbels under the chin. The neck is large and muscular with scattered enlarged conical tubercles over a covering of smaller flat tubercles. The mature carapace is robust, thick and smoothly rounded anteriorly, and generally oval in shape. The posterior margin of the carapace is rounded in shape in Elseya jukesi rather than being acutely tapered (as in Elseya dentata), and the body-form in Elseya jukesi is much more depressed than is the case in Elseya dentata. Additionally, there is slight upturning at the lateral marginals but the posterior of the carapace is largely unserrated. The plastron is always long and relatively narrow, being widest at the bridge and gently tapering both anteriorly and posteriorly, although the anterior plastral lobe does tend to slightly widen with age. The intergular shield completely separates the gulars, and is longer than wide, and much narrower than the adjacent gular shields. Hatchlings differ somewhat in that they have a noticeably serrated posterior margin to the carapace and fairly prominent central ridging (both characters which are lost with age), and some lateral upturning to the carapace as well. In hatchling and immature specimens, the carapace is pale to light brown or olive-brown, with each costal and vertebral shield having a small, pale-edged blackish or dark brown spot. With age the spotting disappears, and the overall carapace colour changes to brownish-red when immature to a fairly uniform very dark brown in the adult condition. Mature individuals have the dorsal colour of the head and neck a uniform dark greyish-brown, and no facial striping. However, the lateral part of the head and neck are usually at least in part much paler - a sort of patchy whitish - or may even be piebald or blotched in pattern; older specimens may be almost totally white on the anterior part of the neck. The iris is brownish without flecking, with a very light inner ring. Hatchlings or juveniles on the other hand, may have a fairly plain, greyish-brown head and neck. Usually the pattern is simple in juveniles, with only the upper margin of the tympanic area having a faint whitish crescent pattern, and the temporals and a few enlarged tubercles being a soft olive-green. The ventral colouration differs significantly in Elseya jukesi, being very pale creamish to bone-white on the plastron and is without pattern, unlike other members of the dentata-complex which are either very dark and usually patterned. Elseya jukesi attains a slightly larger maximum carapace length than Elseya dentata from the Victoria River system, reaching around 350 mm., but this size would be exceptional, as most mature specimens are only about 300mm. The holotype is an adult specimen in the Australian Museum. As is the case with other members of the dentata-complex, Elseya jukesi inhabits permanently flowing freshwater rivers, and may be found occupying both deep-water rocky pools as well as on the muddy or sandy bottoms of shallower waters. This is also a largely diurnal species that basks at the surface of the water or on occasions on exposed rocks or logs. During late afternoon and early evening specimens may be observed apparently foraging in the shallower waters adjacent to larger pools. When disturbed, this turtle will rapidly swim into deeper water or hide under submerged boulders and logs or beneath eroded river banks. Its reproductive biology is at present poorly known, but like E. dentata it would likely produce about 10 eggs in a clutch around the end of the Wet Season (February-May), and these probably would hatch after about 4 months incubation. Mature specimens are mainly herbivorous, feeding on various fruits and flowers that fall into the water from riparian vegetation (such as Pandanus), as well as aquatic weeds, and on occasions carrion but juveniles and immature specimens feed largely on aquatic invertebrates. Captive adult specimens also consume a variety of invertebrates, as well as small fish and raw meat. Like all other turtles, Elseya jukesi is protected under Territory Parks and Wildlife Conservation Act (1998). The population that has been previously identified as Elseya dentata from the Roper River is likely an undescribed species (although some consider this to be part of the distribution of Elseya lavarackorum). The populations in the Nicholson, Gregory and possibly the Leichhardt Rivers have been recently referred to Elseya lavarackorum (which see). Etymology: The specific epithet of 'jukesi' honours Australian naturalist Brian Jukes, a past resident of the area. Lavarack's Turtle Elseya lavarackorum (White and Archer, 1994) The populations of the Elseya dentata complex known from the river systems in the north-eastern NT and northern Queensland that drain into the Gulf of Carpentaria are taxonomically enigmatic. They have been regarded as an undescribed species until relatively recently, when it was discovered that the description of a fossil turtle from the Pleistocene Era actually represented the living species. This species is nevertheless closely related to Elseya dentata, and the major difference linking the species to the fossil species is the bone structure of the plastron. Both the fossil species and this member of the dentata complex share the same undulating suture condition between the pectoral and humeral shields, rather than the straight suture condition as in Elseya dentata. The Gulf species also reaches a very large size that is comparable to the fossil type. Diagnosis: In keeping with other members of the dentata complex, the head is very broad and deep, with a very wide mandibular symphysis and a distinct median alveolar ridge on the upper jaw. The horny plate on top of the head does not extend laterally and there are two small white barbels under the chin. The neck is large and muscular with scattered enlarged rounded or conical tubercles over a covering of smaller flat tubercles. The mature carapace is robust, thick and smoothly rounded anteriorly, generally oval in shape and with some posterior expansion. Additionally, there is only the slightest upturning at the lateral marginals but the posterior of the carapace is largely unserrated. In general shape, the posterior margin of the carapace is rounded in shape. The plastron is always long and relatively narrow, being widest at the bridge and gently tapering both anteriorly and posteriorly, although the anterior plastral lobe does tend to slightly widen with age. The intergular shield completely separates the gulars, and is longer than wide, and much narrower than the adjacent gular shields. Hatchlings differ somewhat in that they have a noticeably serrated posterior margin to the carapace and fairly prominent central ridging (both characters which are lost with age), and some lateral upturning to the carapace as well. In immature specimens, the carapace is pale to light brown, but with age it changes to very dark brown in colouration. Mature individuals have the dorsal colour of the head and neck a uniform dark greyish-brown and the jaws yellowish. The throat and lower neck is white, and the white throat colour extends upwards to the back of the mouth. There is no facial striping, but there is a clear mid-lateral line of demarcation on the neck between the ventral and dorsal colours. The iris is pale brownish, with a very light inner ring and has a distinct median brown spot (either side of the pupil). The ventral (plastron) colouration is creamish white and largely without pattern in both sexes. Elseya lavarackorum attains a maximum carapace length of around 400 mm., but this size would be exceptional, as most mature specimens are only about 340 mm. It is known principally from the Nicholson River system of north-western Queensland and north-eastern Northern Territory. The populations of the Elseya dentata complex inhabiting the Gregory River and possibly the Leichhardt River systems as well as other rivers that enter the Gulf of Carpentaria around lower Cape York Peninsula are also tentatively considered to be referable to Elseya lavarackorum. This species lives only in a few deep-water tropical rivers with either sandy, rocky or muddy bottoms. Their rivers may be associated with spectacular rocky gorges and have rich tropical monsoon or savanna vegetation fringing the watercourse. It is a diurnal as well as nocturnal turtle that lives mainly in the slower flowing or still water conditions of its habitat - often in larger waterholes at the base of low rocky rapids or falls. Specimens will bask on exposed rocks and logs, but will rapidly retreat to the safety of deeper water or under overhanging river banks when disturbed. No direct reproductive information is currently available. If this species is as similar to E. dentata reproductively as it is morphologically, then it probably would produce about 10 eggs in a clutch around the end of the Wet Season (February-May), and the eggs would hatch after about 4 months incubation. E. lavarackorum is mainly herbivorous, feeding on various fruits that fall into the water from riparian vegetation (such as Pandanus), as well as aquatic weeds. Captive specimens also consume a range of aquatic invertebrates, small fish and carrion. This species is protected under the Territory Parks and Wildlife Conservation Act (1998) and the Qld Nature Conservation Act (1992). Stirling's Turtle Elseya stirlingi Wells and Wellington, 1985 Diagnosis: This is a large, heavy-bodied species of freshwater turtle that bears some similarities to its congenor Elseya dentata. As in the case of E. dentata, the head of Elseya stirlingi is very broad and deep, with a very wide mandibular symphysis and a distinct median alveolar ridge on the upper jaw. The horny plate on top of the head does not extend laterally and there are two small white barbels under the chin. The neck is large and muscular with scattered enlarged conical tubercles over a covering of smaller flat tubercles. In general shape, the lateral edge of the mature female carapace of Elseya stirlingi is distinctly straight-edged, giving this species a rather oblong and comparatively broader shape than Elseya dentata. This is most unlike the condition in E. dentata females, where the carapace is somewhat oval-shaped with the posterior margin of the carapace acutely tapered and more depressed. Generally, Elseya stirlingi is a larger and more heavy-bodied turtle than Elseya dentata. Additionally, in Elseya stirlingi, the dorsal colouration is very dark in mature specimens with younger specimens marbled with darker brown or black. The ventral colouration (plastron) is unpatterned and varies from bone-white in juveniles to bluish in immatures through to the mature condition of bluish-black, to very dark greyish or even totally black in old individuals. In marked contrast, Elseya dentata has a distinctive piebald pattern ventrally. In Elseya stirlingi the iris colour darkens with age, but always has a very light inner ring, and is much darker brownish than in Elseya dentata and always lacks the distinctive flecking pattern of E. dentata as well. Elseya stirlingi attains a maximum carapace length of around 380 mm, but males are much smaller than females as is the case with the entire E. dentata complex. This species is mainly confined to the eastern flowing river systems (such as the South and North Johnstone Rivers, and the Barron River) of the Atherton Tableland of north-eastern Queensland. It inhabits fast-flowing watercourses, and may be found occupying both deep-water pools at the base of waterfalls as well as amongst the rocky bottoms of rapids. This is a largely diurnal species that basks at the surface of the water or on occasions on exposed rocks or logs. During late afternoon and early evening specimens may be observed apparently foraging in the shallower waters adjacent to larger pools. When disturbed, this turtle will rapidly swim into deeper water or hide under submerged boulders and logs or beneath eroded river banks. It is believed that about 10 eggs in a clutch are layed around the end of the Wet Season (February-May), and these hatch after about 4 months incubation. Mature specimens are mainly herbivorous, feeding on various fruits that fall into the water from riparian vegetation, as well as aquatic weeds, and on occasions carrion but juveniles and immature specimens feed largely on aquatic invertebrates. Captive adult specimens also consume a variety of invertebrates, as well as small fish and raw meat. Elseya stirlingi is protected under the Qld Nature Conservation Act (1992).
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